docs: def _format_title_string(self, title_string):
          """ format mplayer's title """
          if "StreamTitle='" in title_string:
              tmp = title_string[title_string.find("StreamTitle='"):].replace("StreamTitle='", self.icy_title_prefix)
              ret_string = tmp[:tmp.find("';")]
          else:
              ret_string = title_string
          if '"artist":"' in ret_string:
              """ work on format:
                  ICY Info: START_SONG='{"artist":"Clelia Cafiero","title":"M. Mussorgsky-Quadri di un'esposizione"}';
                  Fund on "ClassicaViva Web Radio: Classical"
              """
              ret_string = self.icy_title_prefix + ret_string[ret_string.find('"artist":')+10:].replace('","title":"', ' - ').replace('"}\';', '')
          return self._title_string_format_text_tag(ret_string)